clk: hi3620: Fix a typo in one variable name

The script "checkpatch.pl" pointed information out like the following.

CHECK: 'seperated' may be misspelled - perhaps 'separated'?

Thus rename the affected variable.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>